1. Field of the Invention
The present invention relates to an antenna coupling device for a mobile terminal, and more particularly to an antenna coupling device for a mobile terminal which is configured to selectively restrain an antenna coupling member fitted in an antenna housing to rotate the antenna coupling member by rotation of an antenna of the mobile terminal.
2. Description of the Related Art
Generally, a “mobile communication terminal” is a device adapted to allow the user to conduct wireless communication with a counterpart. Such a mobile communication terminal includes a hand held phone (HHP), a cordless telephone 2 (CT-2), a cellular phone, a digital phone, a personal communication system (PCS) phone, a personal digital assistant (PDA), etc. These mobile wireless terminals are classified into a bar type, a flip type, and a folder type in terms of their outer structures. Such conventional mobile terminals are essentially equipped with an antenna unit, a data input/output unit, and a data transmitting/receiving unit. For the data input/output unit, a liquid crystal display (LCD) is commonly used. For the data input/output unit, a key pad or touch screen is commonly used. Basically, the keypad used to input data has an arrangement of a plurality of keys including a conversation start button, that is, a send (SND) key, a cancel key, a correction or clear (CLR) key, numeral keys, character keys, an end (END) key, function keys, a power (PWR) key, etc.
The antenna unit is mounted to a desired portion of a terminal body in the mobile terminal in order to receive a signal transmitted to the terminal. For such an antenna unit, a retractable antenna is mainly used which is a combination of a whip antenna and a helical antenna. An example of such a retractable antenna is illustrated in FIG. 1. As shown in FIG. 1, the retractable antenna includes a whip antenna 4 having a dummy rod 4a, a rod antenna 4b, and an antenna stopper 4c, and a helical antenna 5 having an antenna housing 5a internally provided with helical coils, and an antenna coupling member 5b coupled to an antenna bushing 2a fixed to a lower case frame 2 included in a terminal body 1 of a mobile terminal. The rod antenna 4b extends through the antenna housing 5a and antenna coupling member 5b such that it is extendable from and retractable into the terminal body 1.
Typically, there are two types of antenna coupling devices. In the case illustrated in FIG. 1, the first type antenna coupling device is used. The configuration of this first type antenna coupling device is shown in FIG. 2. In the first type antenna coupling device, the antenna coupling member 5b is formed at the antenna housing 5a such that it is integral with the antenna housing 5a, as shown in FIG. 2. The antenna coupling member 5b is adapted to be threadedly coupled with the antenna bushing 2a fixed to the lower case frame 2. In this case, the antenna has a circular cross-section, as shown in FIG. 3. The second type antenna coupling device is illustrated in FIG. 4. In this second type antenna coupling device, a hook-shaped coupling member 51 is formed at an antenna housing 50 such that it is integral with the antenna housing 50, as shown in FIG. 4. The hook-shaped coupling member 51 is adapted to be engaged, in a hooking fashion, with a rib (not shown) formed at the lower case frame 2. In this case, the antenna may have an oval or rectangular cross-section, as shown in FIG. 5a or 5b. 
Where the first type antenna coupling device is used, the antenna housing having a circular cross-section can be reliably coupled with the antenna bushing in accordance with its rotation during assembly. However, where the antenna housing has an oval or rectangular cross-section a problem arises because it is necessary to use the second type antenna coupling device using the hooking method. Among the problems that arise, the rib may be easily damaged, or the hook coupling member may be inaccurately engaged with the rib. As a result, there may be a clearance space at the antenna housing, resulting in a loose antenna.